1. Field of the Invention
The present invention pertains to balloons having internal valves and in particular to flat film valves.
2. Description of the Related Art
Improvements have been sought in the field of toy balloon manufacture, and in particular toy balloons having internal flat film valves such as that disclosed in U.S. Pat. No. 4,917,646. In that patent, a pre-made valve is positioned on a layer of film which will become the outer wall of a completed balloon assembly. The pre-made valve is provided with a positioning tab, and this tab is heat sealed to the layer of balloon film. Next, the balloon film and the valve film sealed thereto are advanced to a subsequent workstation where a second balloon film is overlaid on the partial assembly and the balloon films are sealed to each other and to the valve. In order to prevent closure of the valve, the pre-made valve must be provided with a layer of heat-resistant ink, at those portions of the valve where heat sealing to the balloon films is performed. As those skilled in the art will appreciate, advancing of the subassembly from one position to another prior to registration of the final balloon components complicates the remaining construction steps needed to complete the balloon assembly, slowing the production process, and requiring increased attention to the design, operation and maintenance of equipment used in the automated manufacture, in an effort to maintain exacting manufacturing tolerances.
Despite these extra efforts, difficulties in maintaining high levels of reliability in processes of the type disclosed in U.S. Pat. No. 4,917,646 have been known to occur. Such difficulties have been observed in valve entrance openings internal to a completed balloon assembly, leaking valves, and valves with impaired openings which are more difficult for a reseller to fill. Further, some resellers prefer to heat seal even self-sealing balloons once filled, as a matter of policy, despite the proven reliability of self-sealing valves to automatically close when the balloon is inflated. Such policies may be employed, for example, where a reseller receives balloons from a variety of different, sometimes unknown sources or when personnel inexperienced with balloon manufacture are employed in a flower shop or novelty shop, for example.